Primitive heart cells migrate from where to form the two endothelial lined tubes?
Primary Cardiogenic field: a horseshoe-shaped zone of splanchnic mesoderm.
What is the earliest sign of the heart?
Two endothelial-lined tubes
Which type of folding brings the two endothelial-lined tubes into the thoracic cavity?
Which type of folding brings the two endothelial-lined tubes together, into the midline?
Lateral body folding
Once Apoptosis occurs to give ONE midline tube in the heart, what three components are composing the primitive heart?
- - Inner endocardial layer
- - Middle layer of cardiac jelly
- - Myocardial layer
What forms the epicardium of the primitive heart?
Mesodermal cells migrating from near the developing liver
Primitive heart receives 3 paired vessels into inflow portion during early development. What are they?
- - Vitelline veins (deoxy blood from yolk sac)
- - Cardinal veins (deoxy blood from body of embryo)
- - Umbilical veins (oxygenated blood from placenta)
Most cranial portion of primitive heart, partitions into aorta and pulmonary trunk, and connects to aortic arches?
What stabilizes the initial heart structure and separates the outflow vessels from the inflow vessels before undergoing programmed cell death?
Once the Dorsal Mesocardium degenerates by apoptosis, what is formed?
Transverse Pericardial Sinus
What does the Transverse Pericardial Sinus allow?
Connection of both sides of the pericardial cavity (thoracic cavity)
Postnatally, where is the Transverse Pericardial Sinus located?
Posterior to both the aorta and pulmonary trunk, and anterior to the superior Vena Cava
Path of circulation through the primitive heart? (5 cranial to caudal differentiations)
In through the inferior sinus venosus -> primitive atrium -> through atrioventricular valve to primitive ventricle -> bulbus cordis truncus arteriosus into aortic sac
In which directions does the caudal atrial portion shift once the heart is beating and is too long to be accommodated in the volume available as a straight tube?
Shifts dorsocranially and to the left. (flips behind tube and goes upward to end up on top, then to the left a little)
What is the term for when the heart lies on the right side of the thorax instead of the left due to abnormal heart looping (2 types), and which one is accompanied by other severe cardiac abnormalities?
- With situs invertus (inverted position of all organs) or Isolated dextrocardia. Isolated dextrocardia is usually associated w/single ventricle, ventricular septic defect, etc.
What are the two origins of the right atrium?
- Original primitive atrium
- Right horn of sinus venosus
All left veins are obliterated during week 5 and by week 10 the left common cardinal vein is obliterated as well. What forms from the remnants of the left sinus horn?
The oblique vein of the left atrium and the coronary sinus
What happens to the right sinus horn after left sinus horn rapidly loses fxn and eventually obliterates?
Enlarges and is incorporated into the posterior wall of the right atrium.